Intergrating HVS perceptual mask for a color image watermark

• Main Authors: Chuang, Hui-Ting, 莊惠婷
• Other Authors: Tsai, Min-Jen
• Format: Others
• Language: zh-TW
• Published: 2010
• Online Access: http://ndltd.ncl.edu.tw/handle/85997206335506022675

碩士 === 國立交通大學 === 資訊管理研究所 === 98 === Recently, many researchers invest in developing digital watermarking technology to secure the ownership and the authenticity of the media. There are mainly two types of watermarking algorithms: visible watermarking and invisible watermarking. In this thesis, we propose a visible watermarking techniques to solve the issue of copyright protection and authentication for digital image. In order to get the best tradeoff between the embedding energy of watermark and the perceptual translucence for visible watermark, the contrast-sensitive function (CSF) and noise visible function (NVF) of perceptual model is applied to the global and local image properties. The perceptual model identifies texture and edge regions to determine the optimal watermark strength at the watermark embedding stage. In addition, the effects of CSF masking which we propose not only fully match with the inverse of CSF, but also have better effects of contrast sensitivity than the traditional square function. The proposed method resolves the problem caused by multiple thresholds . The success is due to the fact that the function of this method is used in place of many thresholds to reduce weights in low frequency domain. From the experimental results, the proposed technique find a searches between visibility,transparency and robustness, these are requirements that visible watermark is usually satisfied . The proposed method not only has better visibility than other algorithms, but also preserves robustness under various signal processing and advanced image recovery attacks. Visual Quality Measurement show good performance for our proposed visible watermark in VSNR,MSSIM and NQM.